The present invention relates to an improved apparatus for controlling an AC power elevator.
A control circuit for a power elevator which employs induction motors for a winding motor and a door motor is shown in FIG. 1.
In FIG. 1, a three-phase AC power source is connected to terminals 1; a drive device 2 is connected to the AC power source at the terminals 1 and is composed of a thyristor, a power transistor, and an electromagnetic contactor, etc.; a winding three-phase induction motor 3 is connected to the drive device 2; a brake wheel 4 is coupled to the motor 3; a brake shoe 5 is provided to face with the outer periphery of the brake wheel 4 and applies a brake force to the brake wheel 4 by the force of a spring (not shown); a brake coil 6 separates the brake shoe 5 from the brake wheel 4 against the force of the spring when the coil 6 is energized; a drive sheave 7 is driven by the motor 3 for a winch; a main rope 8 is engaged on the sheave 7; a cage 9 is coupled to one end of the main rope 8; a cage door 10 opens or closes the entrance of the cage 9; a three-phase induction motor 11 drives the cage door 10 to open or close the cage door 10; a balancing weight 12 is coupled to the other end of the main rope 8; a door motor drive device 13 is inserted between the power source 1 and the motor 11 and is composed of a thyristor, a power transistor, an electromagnetic contactor, etc.; an operation command generator 14 generates a command to start or stop the motor 3 so as to control the gate or the thyristor or the base of the transistor of the drive device 2; and a door command generator 15 generates a command to start or stop the motor 11 so as to control the drive device 13 in a fashion similar to that of the generator 14.
An example of the concrete structure of the drive device 2 is shown in FIG. 2.
In FIG. 2, terminals R, S and T are connected to a three-phase AC power source 1; a rectifier 101 converts a three-phase AC power source voltage into a DC voltage; a smoothing capacitor 102 smooths the DC output of the rectifier 101; an inverter 103 of widely known pulse width modulation type is connected to the DC side of the rectifier 101 and converts a predetermined DC voltage into an alternating current having a variable voltage and variable frequency under the pulse width control; the winding three-phase induction motor 3 is driven by the inverter 103; an inverter 112 for electric power regeneration is connected between the power source at the terminals R, S and T and the output side of the rectifier 101; normally open contacts 118a-118c of the electromagnetic contactor for operation are energized when the cage 9 is started and are deenergized when the cage 9 is stopped; and normally open contacts 119a-119c of the electromagnetic contactor are energized after the contacts 118a-118c of the electromagnetic contactor are energized, and are deenergized after the contacts 118a-118c are deenergized.
FIG. 3 shows an internal circuit diagram of the rectifier 101, wherein the rectifier 101 consists of diodes D.sub.1 -D.sub.6. The rectifier output of the rectifier 101 is smoothed, and is supplied to the inverter 103 illustrated in FIG. 4. In FIG. 4, diodes are connected reversely to transistors Q.sub.1 -Q.sub.6 ; and the inverter is arranged such that the transistors Q.sub.1 -Q.sub.6 sequentially conduct in the operating direction by means of the voltage applied to the bases of the transistors. FIG. 4A shows an electric power regenerative inverter 112. When a cage 9 is regeneratively braked, the AC current generated by a motor 3 is converted by an inverter 103 into a direct current, which is converted to an alternating current by causing the thyristors of the inverter 112 to sequentially conduct, thereby generating a power source voltage.
The drive device 2 is thus constructed. A variety of concrete arrangements of the drive device 13 for the door motor can be considered, and may be constructed in a fashion which is similar to that of the drive device 2.
The detailed circuit diagram of the operation command generator 14 is shown in FIG. 5. This circuit mainly consists of a calling button switch 218, a car direction command generator 219, and a frequency and phase order signal generator 200.
In FIG. 5, when the button switch 218 conducts, a power source voltage Vcc is applied to a speed pattern circuit (SP) so as to charge a capacitor C.sub.1 through a resistor R.sub.1. In this manner, a charging voltage VP shown in FIG. 6 can be obtained. The charging voltage Vp due to the conduction of the button switch 218 is applied to a voltage controlled oscillator 223, which in turns generates an output pulse 222a which is responsive to the voltage Vp.
FIG. 7 shows the waveform diagram of the output pulses at the respective sections in FIG. 5. The output pulse 222a is supplied to a 6 stage Up/Down Counter 224, which in turn generates the output pulses 224a, 224b and 224c shown in FIG. 7. These output pulses 224a, 224b, 224c are formed by a logic IC, and signals 226a to 231a are generated from a decoder 235 which operates in accordance with the truth table shown in the Table I, thereby controlling the inverter 103.
The counter 224 receives a car direction command signal from the car direction command generator 219. The power source voltage Vcc is applied to the counter 224 when the contact (UP) is closed, thereby rotating the induction motor 3 so as to lift the cage of the elevator. When the contact (DN) is closed, the cage is lowered.
More particularly, the output pulses 226a-231a shown in FIG. 7 are outputted from OR gates 226-231, and are used as the gate pulses of the transistors Q.sub.1 -Q.sub.6 of the inverter 103, and the inverter 103 generates the AC power having variable voltage and variable frequency of the phase order corresponding to the car direction.
The operation command generator 14 is thus constructed, thereby controlling the inverter 103 of the drive device 2 and driving the winding induction motor 3.
The door command generator 15 may be constructed in the same manner as the operation command generator 14, and when the generator 15 is constructed in the same manner as the generator 14, the car direction command generator 219 in FIG. 5 may be used as the door opening or closing command generator in such a manner that the UP switch is used as the door OPEN switch, and the DOWN switch is used as the door CLOSE switch. In this case, Vp in FIG. 6 becomes the door opening or closing speed command.
The control circuit for the elevator thus constructed controls the motor 3 by the operation command generator 14 and the drive device 2, thereby starting the cage 9, and the cage 9 is moved to the story to be called and is then stopped. When the cage 9 is stopped, the motor 11 is controlled by the door command generator 15 and the drive device 13, thereby opening the cage door 10. When a predetermined period of time (such as 4 seconds) has elapsed after the cage door 10 is opened, the motor 11 is controlled by the drive device 13, thereby closing the cage door 10. When another calling is generated from another story, the motor 3 is again controlled by the drive device 2, and the cage 9 starts moving.
In this manner, unless a high class elevator is employed, the opening or closing period of the cage door 10 and the operation period of the cage 9 are controlled so as not to be superimposed. Therefore, when induction motors are used for the winding motor 3 and the door motor 11, it is not economical to accommodate the exclusive drive device 13 as the door motor 11.